Alligatorem Cognoscere
by Mykerinos
Summary: Severus Snape is a spy because he isn't attached to anyone. But what if he looses all the things he did have? Chapter 4 is finally up.
1. The Alligator's Legs

Disclaimer: Everything that can be found in the Harry Potter novels, belongs to JK Rowling. The rest is mine. 

Thanks very much to Elissa for beta-reading this chapter. 

..

**Alligatorem Cognoscere**  
_Chapter One: The Alligator's Legs_

He's in the water, you're in the water. Who needs to be afraid? Your eyes widen when you see how fast the alligator swims to get a rat. You should be afraid.. Shouldn't you? You start to swim, and hear the alligator coming after you. "I'll never make it," you think. "Even if I do reach the land, he'll run, and eat me.." Will he? You reach the land, and without looking back, you run. Run! A branch makes you stumble, and you fall on the ground. "This is it," you think, "This is the end." You turn on your back, and to your surprise the alligator still is far away from you. Astonished you look at it, and see he's going terribly slow. Sharp teeth, yes, but very short legs. 

*~*~*~*

"A great welcome to you all!" Albus Dumbledore spoke to the hundreds of students. All of their faces were turned to the man, who in spite of his age talked and acted like somebody half his age. Somebody like Cassius Ingaster. He listened to the speech of the Headmaster, hoping he would soon announce the meal. Cassius hadn't eaten since yesterday night, in the aeroplane. It had been a motley collection of some junk food, vegetables, and pieces of fruit. He wondered what it was that drove the muggles to eat things like that. His thoughts were suddenly interrupted.

"I'm glad to say I've found another DADA teacher, who was willing to teach at Hogwarts. Cassius Ingaster!"

Albus gave Cassius a friendly smile, and he stood up to receive the applause. When he sat down, Albus spoke some final words, and then gave the signal to let the meal appear. Cassius couldn't control himself any longer, and he grabbed everything that looked tasty, to hastily put in his mouth. When he saw some colleagues staring at him, he swallowed some magical beans, and continued his meal, but now somewhat slower. 

Still he felt a piercing gaze, and when he looked up, he saw a man with a hooked nose, pale skin and black, greasy hair, staring at him. As if the guy didn't look bad enough, his expression was one of utter loathing. Cassius gave the man a smile, but he only turned his head away. 

"Man, what's his problem?" Cassius muttered, while pouring some juice. The woman next to him must have had perfect ears, because she could hear Cassius through the laughing of Dumbledore who had just heard a good joke from Professor Flitwick.

"Something wrong?" the woman asked.

"Who's the man with the-" Cassius hesitated. Maybe 'man with the greasy hair' wasn't a good description. "-black robes?" 

"That's Severus Snape, he is the Head of Slytherin House, and Potions Master here." She offered her hand. "Minerva McGonagall, deputy mistress."

"Cassius Ingaster." He didn't think it was necessary to tell her his job. "Why is he looking so acid?"

"Because he _is_ acid."

Cassius saw that it hadn't been her intention to say that, because she quickly shut her mouth. He raised his eyebrow, but didn't ask any further. 

His hunger had been allayed, and when he put down his napkin, the tables emptied, and he realised they had been waiting for him to finish the meal. The students left to their dormitories, and Cassius wanted to leave to his own room too, when he remembered there was a meeting in 10 minutes. He sighed, and headed for the teacher's room. 

Most of the teachers were already in there, and Cassius sat down on a chair around the large marble table, which was standing at the centre of the room. When Albus Dumbledore came in, the rest of the teachers sat down too. Dumbledore walked to the head of the table, and took his place there, after checking everybody was present.

"I shall not beat about the bush." His face was friendly, but his voice stern. "Voldemort has returned, and even though every student is aware of that, I want them to feel safe. So I want to discuss when and where patrols will take place, and who will be conducting them. Minerva, will you take the Hufflepuff section? That's next to your room."

Cassius tried to listen to how everybody was being divided over the different sections of the castle, but he hadn't slept for at least 24 hours, due to the patrolling he had had to do in the muggle aeroplane. Because he was fully concentrated on keeping his eyes open, he didn't notice Albus calling his name. He startled when somebody shook his arm. Confused he looked up. 

"I'm sorry, what were you saying?" he muttered.

Some teachers stifled some chuckles, and Cassius had definitely broken the tensions. The serious look in Dumbledore's eyes had disappeared.

"I said that you will take the east tower, as from tomorrow, of course. It is clear that you've done an excellent job staying awake on the plane, in order to protect the muggles. Please take a rest now, or you won't even be awake during tomorrow's lessons."

Cassius nodded, gratefully, and with a scraping noise he shoved away his chair to give him room to stand, and left the table, receiving compassionate looks.

It was getting dark already, and Cassius had to light his way with his wand to find his way to his room. It was located at the end of a large corridor, in the north tower. When he arrived there, Cassius stared at the door. With a sense of disbelief, he touched the letters of his name, which were engraved in the door. He unlocked door with a spell, and walked into the huge room. 

Cassius had been in the room once before, to unpack his stuff, but it still fascinated him. On the left side stood a large bookcase, with loads of books. On the right side were his bed and his desk, and opposite the door was a fireplace, with a large couch and a table in front of it. Next to it, there was a door that led to a small bathroom.

Cassius walked straight to his bed, and let himself fall on it. He had everything that was needed to fall asleep; A warm bed, an empty head, and he was tired. Still, sleep remained elusive. Probably he just had to get used to this new place. With a feeling he had been laying awake for hours, he stood up from his bed and looked at the clock.

"Five past eleven?!" he exclaimed. "Impossible! I went to bed at 10! I thought it was at least around midnight…" 

He sighed, and fell down on the couch. "I _need_ some sleep, or I will really fall asleep tomorrow." Cassius muttered. Then an idea struck him, and he rose on his feet. "I hope Professor Snape is still awake."

He silently left his room. "_Lumos_," he whispered, and after some searching he found a map of the castle in his case.  He fixed where he was, and where he wanted to be, and then walked down to the dungeons, with his wand stretched forward, sometimes looking on the map. 

When he had only one more corridor to walk through, he put away the map. Carefully Cassius knocked on the massive door. There was no answer. When there was also no response after the second knocking, he put his hands on the door, and leaned towards it. The door was too massive to hear anything through. Cassius startled when he felt himself falling forward, as the door opened. He swallowed, looked around once, and then went in. 

The place wasn't to call 'warm', in fact it was freezing, and everything was dark, except for the top of Cassius' wand. He walked a bit, and studied the various potions. At last he arrived at the blackboard, which seemed rather new. But the dust on top of it made clear that it wasn't new, it was just.. Barely used. Cassius saw another door behind the blackboard and he suddenly burned of curiosity. He was about to enter, when he was startled by somebody clearing his throat. Cassius quickly turned around, to see Severus Snape standing there.

"I see you are awake enough to sneak into my dungeons, Professor Ingaster."

"I wasn't _sneaking_ into your dungeons!" Cassius exclaimed, surprised that the man was jumping to conclusions so soon. "I only wanted a sleeping potion, but you weren't here, and the door was unlocked, so-"

"So you thought you would just go in and a find a sleeping potion in somebody else's room?"

Cassius hesitated. He did make it sound like it was a crime. "Uh, yes."

Severus' eyes narrowed, and he turned to a huge case, and picked out a bottle. "One draught will make you sleep until morning."

Cassius took the bottle, thanked the Potions master, and wanted to leave. When he walked past Severus, the scent of blood penetrated on him, and he roughly turned around. They stared at each other, both of their gazes full of suspicion.

"Good night," Severus said emphatically, and Cassius also found it time to leave.

"Wow," he said to himself as he walked back to his room, "I'll eat my map if that guy isn't evil. Hopefully the potion is a real sleeping potion, and not a poisoning one."

*~*~*~*

"My name is Cassius Ingaster, and I hope I can last here longer than your previous DADA teachers. I-"

A girl with brown hair and a pile of books and notes on her desk, put up her hand. Cassius was surprised there was a question already.

"Yes?" he asked.

"Isn't Cassius Latin for 'vain'?"

"That's right. I didn't know you had Latin here at school too. Five points for Gryffindor." Cassius wanted to start today's subject, but the girl continued.

"Well, we haven't got any Latin, but Latin is a very interesting language, because it returns everywhere. So when I'm not working ahead, I try to get up with Latin, and I've just read this excellent book about the history of the Romans-"

"Thank you, I get the point," Cassius interrupted her, afraid she would be talking for the rest of the hour. "What's your name?"

"Hermione Granger, sir." 

"Okay Hermione, could you step forward? I'd like to demonstrate a few things. And you too, please." He pointed at a boy with black hair and glasses. When he saw the scar, Cassius realised this was Harry Potter.

Both stood up, and walked to the blackboard. Cassius let the two fight a short duel, to find out what spells they already knew, and he taught them some new. The rest of the lesson they spent practicing the _convisibility _spell, which made you invisible for a short time, enough time to surprise the enemy with a spell from an other direction.

Later that day, when Cassius was about to teach the Huffepuffs the same spell, the door suddenly flew open, and Professor Flitwick stood there, sweat running down his face.

"Professor Ingaster, the Headmaster asks you to come!" the small professor squeaked. Cassius opened his mouth to say something, but shut it. He turned his head to the students, who were talking quietly. 

"Read through page 25 to 39 and answer the questions on pages 40 and 41." He stood up from his desk, and followed Flitwick, who was nervously wringing his hands. 

"What has happened?" he asked.

"Emergency! Death eaters are taking some halfbloods hostage!"

"What?!" Cassius exclaimed shocked. "How did they come in? Where are they? How are the hostages?"

Flitwick shrugged his shoulders. "I don't know!"

As they ran into the Great Hall, they saw many of the staff were involved in a tough fight with some Death Eaters. All of the Death Eaters were masked, and their bodies were covered in black robes. Those of them who weren't fighting, were keeping an eye on the students who were bound on the wall. All together there were 14 Death Eaters, Cassius counted. Noise could be heard from all corners of the Great Hall; it was a mix of frightened screaming, dark laughter, the shouting of spells and curses, and the groaning when somebody was hit. Cassius saw Dumbledore on the other side of the hall, and the fire in his eyes could even be seen from a distance. 

Cassius tightened the grip around his wand, and pointed it menacingly at a Death Eater who was about to cast a (probably very nasty) spell on a colleague, who was already on the ground.

"I wouldn't do that if I were you," Cassius said, grateful of the calmness in his voice. As a response the Death Eater directed his wand at Cassius. Before he could react, the black figure had cursed him. 

"_Crucio,_" was the last thing Cassius heard before he felt pain racing through all his bones, bones that he hadn't known of, until now. He let himself fall on the ground, hoping the pain would ease there a bit, but it didn't. Every touch with the floor made him feel like his skin was burning, but trying to get up was a hopeless task. He closed his eyes, squeezed his nails into his palms and screamed in an attempt to scream the pain out of his body, but nothing helped. Through all the noise he could hear a familiar voice shouting: 

"You! What are you doing?" It was a familiar voice, but Cassius couldn't place where he knew it from. As sudden as the pain had come, it disappeared. When Cassius opened his eyes again, he saw another Death Eater approaching the one who had cursed Cassius.

"We've got more important things to do," he said, and pulled the other away. Cassius inquisitively stared at the tall death eater, and then it dawned on him. 

"Severus!" he gasped when he and the other returned to the group of Death Eaters. 

Still feeling like he had just fallen from a great height, Cassius stood up to see more wizards arrive. The Death Eaters were now on the losing side, and suddenly there was a loud noise and a very sharp light, which made Cassius fall on the ground again, desperately trying to keep his eyes from burning away. When the light had faded away, there were no more Death Eaters around. Some teachers went out to ensure the Death Eaters had in fact left, but Dumbledore told them not to. 

"They're already gone, thank Merlin. We are very lucky to still be alive. And to have all of our students unharmed. God knows why they left them here."

Some wizards objected, but the Headmaster insisted. The students were not hurt, only terribly shocked, if not traumatized.

When Dumbledore went to his office to arrange things, Cassius stopped him. 

"Professor, I need to talk to you. It's urgent."

Dumbledore looked at him for a moment, then nodded, and walked to the office. When they had arrived, they both took a seat. 

The portraits of the past headmasters which had once looked so cheerful, now all had a serious, grave look in their eyes, and on their faces, just like the headmaster sitting in front of Cassius. His brows were furrowed deeper now than ever, which made Cassius shiver. Fawkes silently sat on top of its cage, and if he hadn't known any better, Cassius would have sworn it was a sculpture instead of a living phoenix.

When Cassius went to start, there was a knock on the door. 

"Come in, Severus," Dumbledore said, and the door opened. Severus looked suspiciously from Cassius to Dumbledore, and then closed the door behind.

"I assume that your message is concerning Professor Snape?" Dumbledore asked Cassius, who nodded puzzled.

"I-" he started hesitantly, "I thought.. You know he is a Death Eater?"

It was Dumbledore's turn to nod.

"And you're okay with it??" Cassius stood up, his hands grabbing his head in an attempt to help himself understand.

Dumbledore remained silent.

"What? You're not part of some sort of plot, are you?!"

Severus let out a noise of annoyance, and to Cassius' terror Dumbledore nodded again. 

"You'd better explain it to him, before he starts gossip.." Severus glanced at Cassius. Dumbledore nodded for the third time.

"Severus is an official spy for the Ministry. He passes through information. Only a few people know about it, and normally I would cast obliterate on you, but I trust you will not tell anyone about this."

"Oh," Cassius said daftly, after a short moment of silence. Questions popped into his head, and he thought he'd better ask them now. "Why Professor Snape?"

"He was the best candidate." Headmaster simply answered. It wasn't the complete answer Cassius had hoped for. Severus stepped forward. 

"Now, if you're finished, I'd like to discuss some things with the Headmaster." he said, folding his arms and staring at Cassius.

"Ah.. Sure." Cassius wasn't finished, but he stood up, and left the office. At the end of the corridor he stopped, sighed, and leaned against the wall. 

Although he felt he had been standing there for some time, fifteen minutes had barely passed when he heard heavy footsteps. He quickly stood up again, and saw Severus approaching. He stopped when he saw Cassius. 

"What?" he asked icily. 

Cassius nervously shuffled his feet, and stared at the wall opposite him. 

"I apologise." When there was no response, Cassius looked up. Severus looked really infuriated, and Cassius could now also see his yellow teeth. "For judging you on what I saw." He immediately regretted his words. "Not that you look evil, of course. You must be very loyal if you're ready to undertake such a dangerous task."

"Yes," Snape said in a low voice. "Dumbledore is a very trusting person. I'm afraid that that can be both a good and bad quality."

Before Cassius could ask what he meant, Severus walked past him. 


	2. The Alligator's Eyes

**Alligatorem Cognoscere**  
_Chapter Two: The Alligator's Eyes_

_A tree-trunk laying in the water… The tree-trunk knows you're there, that you're staring at him, and trying to get to know a bit more about the creature in the water. But the tree-trunk does not want you to know more about him, because he who is open, will be hurt. Unfortunately his instinct tells the trunk to open his eyes. You look into his eyes, by which you give him the opportunity to look into your soul. Now you know a bit more about that trunk, but the trunk knows everything about you. Was that a good move? _

*~*~*~*

When Cassius walked into his classroom, the 1st years were already there. Before Cassius could even open his mouth, all 20 children put up their hands.

"Yes?" Cassius said, pointing vaguely at a student, so vaguely that other students also felt addressed, and everybody started to shout questions in a roaring muddle.

"SILENCE!" Cassius shouted, and everybody abruptly shut their mouths.

"Good," Cassius sighed, and pointed at the boy sitting in front of him. "You're first." Once again he had made a bad decision, because the boy attacked him with, it seemed, hundreds of questions, all about the same subject. The attack on the school hadn't remained a secret. Cassius would have answered all of the questions, if Dumbledore had forbidden him from doing so.

"I'm sorry, I can't give you any more information." Cassius shrugged his shoulders and quickly started the lesson before anyone could protest. Thankfully the rest of the lesson passed without any trouble.

The first year Ravenclaws weren't the only ones who wanted to know more about the Death Eaters. All his classes, except for the Slytherins, were the same, and asked him questions he couldn't answer. 

After class Cassius didn't go to supper. He had an empty feeling in his stomach, but he knew food couldn't fill. Because of the patrolling last night, he again hadn't been able to sleep well. Or maybe it had just been the things that had happened that day.

There was a knock on the door, when he asked whoever it was to come in, it was Sally Winters, a first year Gryffindor. 

"Hullo," Cassius said, wondering what the girl was doing here. 

"Hello Professor," the girl responded, staring at her feet. "You..- I need to learn some spells to defend myself from dark magic. Please?" She said it like it was no big deal.

"Oh." It was all Cassius could say for a moment. "Well, it's good that you're so studious, but you'll learn those spells soon enough."

"But I'd like to learn them now, before it's too late!" The girl sat down, and desperately stared at the table.

"Oh, come on, aren't you exaggerating things a bit now?" Cassius laughed, another mistake. The girl burst into tears, startling Cassius. "Okay, maybe you wasn't.." he said under his breath.

"I'm a half-blood, and everybody knows You-Know-Who first goes after the half-bloods! Half of my family was killed by death eaters, and I thought I was safe at Hogwarts! Now I know I am not, I need to find another way to protect myself, as nobody wants to tell me how they got in."

Cassius felt tears burning in his eyes. He couldn't take it when people cried. He quickly walked to the girl to put an arm around her, feeling pity for her. "I'm so sorry," he said, and he meant it. "But don't worry, Dumbledore has got everything perfectly under control. You won't need any spells to protect yourself, there are enough people who'll look out for you and the other half-bloods."

It had probably reassured her, because she stopped sobbing. When Cassius looked up, he saw Severus standing in the opening of the door. "Are you two ready?" he asked in a tone. Cassius gave one more look to the child, stood up, and walked with Severus out of the room. 

"Well, it seems the beloved Professor isn't as good as he looks." Severus sneered, with a small hint of amusement in his voice.

"What do you mean?" Cassius asked, wiping away the tears from his eyes. 

"You wasn't really honest to the girl, were you? Dumbledore has no idea how to prevent another attack."

Cassius wasn't in the mood for going into that. "Where are we going?"

"Dumbledore." Severus answered, the amusement gone.

From Cassius' classroom to Dumbledore's office was a pretty long distance, and Cassius hated the silence.

"So, why does Dumbledore send you to get me?" he asked.

"Because he wants to talk to both of us."

"Oh, of course." With short answers like that you quickly get through your subjects of discussion. Cassius studied Severus. Close up, his look was even sourer. And the way he walked… Like he was full of negative energy. Cassius tried to imitate Severus's staring at nothing.

"What are you doing?" Severus asked annoyed, and Cassius moved back. 

"N-nothing! I only thought there was something on your cheek." If he hadn't realised just in time how silly it would be, he would have slapped himself in the face. That was the stupidest excuse ever, and Severus probably thought the same. He stared at Cassius like he was paranoid, and Cassius wished you could apparate on Hogwarts ground. Suddenly he became aware of a strong smell. He sniffed, and realised it was the smell of herbs, coming from Severus. *Good,* he thought, grinning. *The man at least doesn't stink.*

They finally arrived at Dumbledore's office. This time, Albus had a smile on his face again, and he chuckled when a surprised Cassius and an irritated Severus came in.

"Hurry, Albus, I've got more work to do," Severus said while he sat down. Dumbledore suddenly burst out in loud laughter, and the two other men looked puzzled.

"I've just got a call from Mad-Eye Moody—the real one, I hope—" he added, more laughter following. "He told me this fantastic joke-"

"Get to the point," Severus interrupted, and Albus stopped giggling. He folded his arms, and leaned back in his chair.

"You're right, Severus. As you already know, next weekend the students go to Hogsmeade. Normally Professor McGonagall, Sprout, and Flitwick lead the students to it, but under the current circumstances I think it's better that you two join them." He raised his hand to keep Severus from objecting, and continued. "You two are well-known to be good at the Dark Arts, and if it comes to an attack, then I think that you will be more use than any other professor at this school. Everybody ought to stay together, but I know there will be a few who try to escape anyway."

"Can't you get somebody else do it? You know how I feel about sunlight. And if you just consulted with Sybill, you know precisely." The sarcasm was too strong to not be noticed, even by the headmaster. There was pity in his eyes, but Cassius didn't know whom he was pitying; Sybill or Severus. 

"Severus, don't raise objections. Now that Voldemort knows how to break into Hogwarts, we should be extra careful. Forewarned is forearmed."

Cassius looked at Severus, who nodded.

"In that case I'll need to transform again," Severus sighed. If looks could kill, Albus would've been worse than dead. 

"Transform?" Cassius asked, his eyebrows raising. Both Albus and Severus looked up. It seemed that they had forgotten there was anyone else in the room. The headmaster unfolded his arms, and smiled. 

"If Severus wants to fight against the death eaters, he can't do that as himself." he said.

"-Because that would reveal him as a betrayer," Cassius finished the explanation, in an attempt to show he was able to figure things out on his own, with some help. 

"A spy, yes." Severus corrected, glaring at Cassius. "I'll transform into somebody else when there are Death Eaters or signals of Death Eaters near."

"Well," Dumbledore stood up and rubbed his hands. "If that's settled, than I have one more favour to ask. Can you buy me these?" He handed over a piece of parchment to Severus, who read it through. He angrily stood up, his chair falling on the ground.

"I am your employee, Albus, not your slave or household help." he dangerously hissed, threw the parchment to Cassius, and then stalked out of the office. Cassius picked up the parchment, and also read it. He couldn't suppress a grin. "Sure we'll get them for you," he chuckled, and Dumbledore nodded thankfully. When he read it again, he laughed louder. "_I'm running out of socks, could you get me 2 pair of every colour they have? Just say it's for me, then they'll put it on my bill._", the parchment read.

*~*~*~*

Cassius walked into the laundry room, with his dirty clothes in his hands. He put it on the board with his name on it, and the laundry immediately disappeared. Where the clothes had been, there was now a small house-elf sitting, with a headphone and microphone. "A small delivery, they'll be ready in 2 minutes, sir!" the elf squeaked, and Cassius nodded. He looked around, and saw a huge basket on the plate of Severus Snape. It was closed. Cassius bit his lip. "_Don't,"_ a voice in his head said. _"You've got nothing to do with him, and certainly not with his laundry."_

He bit his lip a bit harder, sighed, and then walked to the basket. Not listening to the screaming of the voice in his head, he opened the basket with a simple spell, and picked out a robe. There was nothing unusual to see, but when he looked some closer, he saw red spots on it. The memory of the smell of blood popped into his head again.

"I don't know why you're searching in _my_ laundry," the sharp voice of Severus Snape could be heard throughout the room, but also through Cassius' bones, and he quickly turned around. "But I can assure you there are merely robes in it." 

Cassius reddened, and he quickly threw the robe back in the basket. "I- I wasn't trying to..- You're underwear doesn't interest me at all,-" He winced at the thought. "-Please stop drawing conclusions.. I was only wondering where that smell of _blood_ came from."

Severus stared at him for a moment, then walked to the basket and grabbed it, but Cassius held on to it. "The soap hasn't worked, has it? I know you're a spy, but are you also allowed to kill people?"

"I haven't killed anyone. Now who is jumping to conclusions?" 

Cassius was surprised by the man's certainty. It didn't sound like a denial, more like a fact. He let go the basket, but went after Severus when he left the room.

"Okay, you got me there. Can I just ask you some more things?" Without waiting for an answer, Cassius continued. "I haven't been in Hogsmeade before, so could you show me where that clothes shop is?" 

"_Now_?" Severus asked annoyed. 

"No, of course not now. When we get there." When Severus didn't respond, Cassius just took that as a yes. "Okay, and why did you explode when the Headmaster asked us to buy the socks? It's not that you have to make a trip around the world to get them."

With an aggressive move Severus turned to Cassius. Cassius had to look up a bit, as Severus was some inches taller. 

"When Albus says _'socks in every colour'_, then he really means in _every_ colour. Have you got any idea how many different colours there are in the wizarding world?" Severus barely whispered, and Cassius lifted his eyebrow.

"Probably many, or you wouldn't have overreacted like this." 

Severus gave him one more penetrating look, and then left. Cassius sighed. "He's unbelievable." He walked back to the laundry room, and he froze when he saw what had happened to his laundry. Everything had shrunk.. He walked to the plate, and then gave it a punch. "Stupid elves! What was the temperature you used?!"

*~*~*~*

"I didn't know there were so many students going to Hogsmeade," Cassius sighed, desperately trying to count the dozens of children who kept moving. "Okay, we first go to that candy shop there. Everyone who wants to go, go now!" Cassius' voice could be heard by every student now, thanks to the Sonorous spell. All of the children wanted to buy candy, and of course they didn't fit into the shop. Severus divided the group into smaller ones, and after an hour everybody was provided with candy in all shapes and all tastes. Chocolate frogs jumped around while the group quickly moved to another shop. When the last group came out, Cassius heard Severus deducting 10 points. Cassius quickly walked to them. 

"What's wrong?" he asked. A 5th years Gryffindor stood there with bent head, and started to sulk back to the shop. "Wait!" Cassius ordered, feeling Severus was just making a fuss about nothing again. "What's wrong?" 

The boy showed a t-shirt, covered with _'School sucks'_. "Professor Snape won't allow me to keep it.." the boy sighed. Cassius repeated the sigh. 

"10 points to Gryffindor." Cassius said, and wanted to walk away. But he was pulled back on his sleeve. 

"What do you think you're doing?" asked Severus in a menacing voice.

"I'm rectifying your mistake, that's all." Cassius answered, fists clenching.

"There was no need to rectify anything, because there was no mistake."

"Then was it just in a fit of insanity you took away those points?"

"No, it was because I will not tolerate shirts that are trying to insult a teacher. Students must bear the consequences when they do."

"I didn't know teachers were allowed to take away points because the student's opinions are different from the teacher's." Cassius broke away from Severus, who was pulling his sleeve to the ground.

"They are, if the opinion can be seen as offensive."

"Well, I know you think much of yourself, but you are just a teacher, not a school. The only one who has the right to take this shirt as an insult, is the Headmaster, but I'm sure he would laugh about this."

Suddenly there was the high voice of Minerva McGonagall calling. "Severus, Cassius! What for Merlin's sake are you two doing?!" She pushed through the students, and as Cassius was nearest, she tightly grabbed his arm, then with her free hand she grabbed Severus' arm too. The students quickly jumped away, and Minerva dragged her two colleagues into a narrow lane. There Severus roughly broke away from her, and to Cassius' relief she also let him go.

"Well, could somebody explain what that was about?"

Before anyone could answer, a girl appeared. She had red hair and freckles, so it probably was a Weasley. "Professors!" she squeaked, "Ron, Harry and Hermione are gone!" 


	3. The Alligator's Scales

This time I only have to thank Mystical Dragon for reviewing the second chapter ^_^ Anyway, are you also the Mystical Dragon that wrote that Snape-fic? I mean the Snape-fic where in the beginning Severus' mom tries to escape from death eaters (I can't remember the name anymore..). I've read the first part, then bookmarked it. I'll certainly read it when I find some time. 

Didn't I say I couldn't keep deadlines? Now you see I spoke the truth! I was lazy, and thought I could postpone it until the last day. Of course that didn't work. So no more deadlines for me. Sorry if this chapter is a little bit short..

Alligatorem Cognoscere  
_Chapter Three: The Alligator's Scales_ The scales on the alligator's back aren't very dangerous, but an alligator with scales looks more dangerous than one without scales. Scales keep you from coming close, they keep you from stroking his back. But when you take that first step, and touch a scale, you'll feel it's not sharp, and no danger to you at all. It's just there as a shield. 

*~*~*~*

"What do you mean, _gone_?" Severus spat, and the girl, who Cassius now recognised as Ginny, reddened. 

"They said they would be gone for a minute, and begged me not to tell anyone! But now they're already gone for half an hour…"

There was a short silence as Minerva smacked her hand to her mouth, and Severus folded his arms. "So," he said, scowling at the girl, "Orders of the famous Harry Potter are more important than school rules?"

Cassius saw how guilty Ginny was feeling, and he wanted to say something to reassure her a bit, but he couldn't find the right words. "They probably are just wandering about," he tried, but it didn't help. Minerva shook her head, Severus snorted, and Ginny just stared at the ground while tears fell down.

"We need to search for them, now." Minerva said. It was a decision, not a suggestion, but Cassius still nodded. 

"I'll call the rest of the professors," Cassius said, and started to walk away when Severus stopped him. 

"And then what? You want to leave the students alone while we go searching, so they're an easy target for an attack?" 

"You're right, somebody will have to stay with them. What about you, Severus?" Minerva sounded serious, but Cassius rose his hand. Minerva, Severus and Ginny surprised looked up. 

"What?" Severus said annoyed. 

"You have to remember your transformation, right? When the Death Eaters attack, you can't transform in front of all your students." Cassius added quietly, so Ginny couldn't hear. He waited for a response, but Severus only nodded. 

"Yes, Professor Ingaster would do a better job."

Cassius swallowed, imagining panicky students, crying students, students running away, and him standing in the middle of it, shouting everything would be fine, in an attempt to calm them down. Cassius quickly shook his head. "I don't think so. I mean, I'm a new face to the students, and I think they are likely to trust you, Minerva, more than they trust me." 

Minerva considered it for a moment, and then agreed. "Alright," she said while she walked away with Ginny, "You'll go searching with some other teachers, and I'll keep an eye on the students with the rest."

Cassius walked out of the lane, and started to ask passers-by if they had seen Harry Potter (as far as it goes it was a lucky thing that Harry was the one to be missing: Everybody knew him). After innumerable "No, I'm sorry,"'s, Cassius found a little girl who said she did see something. She pointed in the direction of a shop. Cassius thanked her, and made his way to the shop with all kind of gadgets. His heart started to beat rapidly when he saw Harry standing next to the counter, his face turned to the shop owner. 

"Harry!" Cassius shouted, running to the boy. When he wanted to grab his shoulder, his heart stood still for a moment; Harry was transparent, and Cassius' hand went trough the boy's body.

"Yes, it's looking really real, isn't it?" the shop owner said, and Cassius realized the boy wasn't a human: it was just a projection of the famous Harry Potter.

"Oh- eh, yeah, you can say that.." Cassius stammered. The boy turned around, and smiled to Cassius.

"Hi, I'm Harry! Do you want me to tell about my confrontation with You-Know-Who?"

Blushing furiously, Cassius turned, and left the shop. He watched the passing wizards and witches, and asked a few more times if they had seen Harry Potter with two other kids his age. Nobody had. He sighed as he sat down on a trashcan in an abandoned street. The clamour of the busy street couldn't be heard here, and the wind blew away some garbage. 

"Where would _I _go if I was a 15-year-old.." Cassius asked himself, but the answer came from behind him. 

"Maybe you would go to a place where nobody knows your face, and where you can think in peace. Maybe you would go to a place like this." 

Cassius turned around to see Harry emerging from a side street.

"What has happened?" asked Cassius, and he walked to the boy, who looked exhausted. He was breathing heavily, and he had a strange look in his eyes. There was blood on his face, dirt on his clothes, and his back was curved. He pulled his cloak to give it to Harry, but the boy, looking like an old tramp, just slapped his arm away with a power that Cassius hadn't expected.

"Sorry!" Harry quickly said.

"Never mind.." Cassius responded, too surprised to say something else.

"Professor," Harry said in a serious voice, "I've lost my wand, could I borrow yours for a second? Just to repair my glasses."

Maybe it was just the weird situation, or he was afraid for Harry, but Cassius gave his wand. Immediately Harry pointed his wand at his professor, and started to laugh. "You're so stupid!" he shouted, and laughed louder. He abruptly shut his mouth. Cassius stared at the boy in horror. 

"Harry, let's return to the castle," he said, stretching out his arm to the wand.

"Expelliarmus!" Harry shouted, and Cassius was blown to the ground. That boy really had strong powers. Cassius' head hurt, and when he opened his eyes again, he was seeing some stars. He tried to stand up, but lost his balance and fell back on the ground again. Harry laughed. 

"Where are Ron and Hermione, Harry?" Cassius gasped, and stopped trying to stand up.

"Gone," Harry answered, and walked to Cassius. He didn't look like a tramp now, more like a psychopath. "So, you understand your end has come?" 

Cassius did his best to faint; this all was too strange, and it was happening too fast. Harry's face straightened again, and he sighed, building up some energy. "Avada.-"

There was a flash, and Cassius thought it was the green flash of the Unforgivable Curse, but when it was gone, he didn't feel really dead. There was some groaning, and when Cassius opened his eyes and found he could sit up, he saw a stranger had knocked Harry on the ground, and tied the boy up with a rope that appeared out of nowhere. Suddenly Harry's muscles relaxed, and he let his head hang, and fall on the ground. The stranger looked around, and without paying any attention to Cassius, he ran to the side street where Harry had come from. 

Cassius stood up, and stumbled after the man, wanting to know who he was, what he was doing. When he had reached the corner, he had to grab the wall to not fall again. The stranger was now duelling with another man, dressed as a Death Eater, and Cassius wondered what was going on. First Harry tries to kill him, then a man suddenly appears and saves his life, and then the man fighting against a death eater.

"Ingaster!" shouted the stranger, and he threw something to Cassius. It was his wand. He took a good look at the stranger. His face was young, his eyes shot fire, and the way he jumped away to avoid spells gave away he was very fit. 

Cassius saw the man was on the losing side, he decided to help him. 

"_Furninculus!_" was the first spell he could think of, and the surprised enemy was hit. Sores started to show up everywhere in his face, and the man screamed. The guy who had saved his life now also shot a spell at the Death Eater, who was slammed into the wall. The stranger ran to the death eater, and pulled the man's mask of. He cursed, and then turned to Cassius.

"Send the Ministry an owl, and tell them you've caught Barry Greyland."

"Wait!" Cassius yelled as the stranger turned to go. "I want an explanation!"

The man sighed. "Go ask somebody else," he said, and took off. With mouth hanging open Cassius stared after him. What a silly thing for the man to say. Then he gave a look at the death eater, who seemed to laugh. Cassius sighed, and with a spell he fastened the man, then walked to the nearest shop, and sent an owl to the ministry, like the man had told him to. He ignored the stars and the dizzy feeling, and was glad to bump into Minerva.

"Oh dear, Cassius!" she cried. Cassius felt his strength was almost gone.

"Not now!" he said roughly, interrupting her. "Death Eater is.. There-" pointing where he'd come from. Everything was vague, but Cassius refused to sit down. 

Minerva gave him a sympathetic look. "Poor guy," she muttered, "Let's go to the hospital," 

"No," Cassius said, pushing Minerva away with his last strength. He stumbled over a chair, and fell back. Then everything went black.

*~*~*~*

When Cassius opened his eyes, he really thought he was in heaven. As far as he could see everything was white, and yes—that definitely was an angel. 

"So, I lived well after all.." Cassius smiled. Then his vision sharpened, and he saw the angel was Madame Pomfrey. Minerva sat on a chair next to his bed, but she now stood up. "By Merlin," she said, "He's delirious! Give him something!"

Cassius quickly sat straight up in his bed. "No, I'm okay, really! How long have I been asleep?" 

Madame Pomfrey pushed Cassius back under his blanket. Well, if there was one thing Cassius had learned, then it was not to underestimate the powers of people who don't look very strong. "Just one night." 

Cassius thought through the events that had happened yesterday. Immediately he started to ask questions while Madame Pomfrey examined him. 

"How is Harry? And Hermione and Ron? Have they found that Death Eater? And that stranger, have they thanked him too?"

"Well, I can only answer the first three questions." Minerva said, while she took her seat again, "Yes, Harry, Hermione and Ron are all okay. Professor Snape found Harry in a side street, and his two friends were found a street farther on, both unconscious, but nothing serious. The death eater was taken to the Ministry."

"Thank Merlin." Cassius sighed. "So, when can I leave hospital?"

Poppey twitched her mouth, like she didn't want to discharge him. "This afternoon, I guess. You lost a lot of blood, so take things a little bit easy, or you'll pass out again." 

There was a knock on the door, and Dumbledore came in. His eyes flickered in the morning light, and his beard seemed to be whiter than before.

"Thank you, Minerva, I'll take it from here," he smiled. Minerva left the room, and at the request of the Headmaster, Pomfrey also went to do something else. Albus sighed, and sat down at the chair where Minerva had sat too.

"I thought I'd make sure somebody was here to answer some questions. Severus told me about yesterday," he said, and made a gesture with his hand. "About the Death Eater and Harry," 

Cassius raised his eyebrows. "You mean Severus Snape? But I'm sure I haven't seen him." 

Albus smiled to him. "You have. He has fought against Barry Greyland, and gave you your wand back." 

Cassius opened his mouth. "The transformation.. I'd forgotten about that…"

"He was just in time to save you from Barry..-"

"Barry?" Cassius interrupted Albus. "I thought it was Harry who tried to kill me, or was that a transformation too?"

Albus laughed loudly, and he grabbed Cassius' shoulder. "No, my friend, that Death Eater used a very powerful Imperius curse to make Harry kill you. No, Harry might have special powers, but no dark powers." 

Cassius reddened. "Unbelievable that I wasn't able to figure that out myself…" he sighed. 

"Oh, don't bother about it, you can't know everything," he laughed again. 

"No, I should've at least sensed something wasn't right! After all I'm the Defence Against the Dark Arts teacher." 

"_After all,_" Albus repeated, "it had a happy ending. Nobody's to blame, as there is no problem! Now, if that's okay with you, I'm going back to my office again. I still need to deliver a sermon to Harry and his friends for breaking school rules. But I'll be easy on them; Severus has already deducted 100 points from Gryffindor." He smiled and left the room. Cassius sighed, and stared at the ceiling. 


	4. The Alligator's Species

Alligatorem Cognoscere  
_Chapter Four: The Alligator's Species_

The alligator domineeringly swims around. His senses sharpen when he feels a movement in the water, and he turned to look at a boat that is approaching him. The alligator quietly stays where he is, and doesn't move a single muscle. In the boat are figures moving, figures that are quite big. When it comes too close, the alligator attacks the boat, then he quickly retreats in his hole. If he had been able to, he would have sighed and thought: "I am endangered, so stop bothering me."

*~*~*~*

Cassius stood up from his bed, thanked Poppy, and walked out of the Hospital Wing. He was completely healed, but felt the feeling you have when you get out of hospital; because you think you're still a bit weak, it feels like you are. He walked down the corridors, leading to the dungeons, and stepped into the classroom. Severus Snape looked up from his desk, and Cassius could see the irritation in his eyes. 

"Er- Hello.." Cassius greeted, but he was interrupted by the Potions Master. 

"Dismissed!" he snapped, and Cassius was relieved to see it wasn't meant for him; There were students sitting at the desks in the classroom, convulsively copying texts from their books on large pieces of parchments. They startled at the sound of Professor Snape's voice, and quickly collected their stuff, to rush out of the classroom. 

"What is it this time?" Severus sneered, and Cassius did his best not to step back at the menacing look he was given. 

"I actually wanted to thank you.. And to say I'm sorry."

Severus looked up, his face unreadable. "Sorry what for?"

"Well.. For misjudging you. What you did was very courageous. You would've fit in Gryffindor as well, you know." 

Severus glared at him. "Are you trying to insult me, Ingaster?" he hissed between his teeth. "If so, I would warn you not to try it a second time. Now get out of my classroom." 

Before Cassius could object, he felt some sort of warm, invisible blanket push him backwards. He stretched out his arms to push it away, but it didn't work. 

"It was a compliment, not an insult!" Cassius said, while he kicked the air. He lost his balance, and fell on the ground. He grabbed the leg of a desk, but it was for no use as the desk was just pulled with him. When he had reached the exit, he quickly held on to the door. But when it closed, Cassius had to let go if he wanted to keep his hands. With the closing of the door, also the invisible power disappeared. Cassius stood up again, and pounded a few times on the massive door. 

"I'm sorry!" he yelled. "I meant that you proved you really are loyal to Dumbledore. Severus? I'm not going to leave, you hear me?" He pounded again. _Alohomora_ didn't help, but Cassius suddenly remembered the door behind the blackboard. Maybe there was another entry. The further he was walking into the corridor, the darker it was becoming. When he couldn't see any more, he touched the wall, and after walking further down the corridor, he found a door. He knocked on it. 

"Hullo?" 

Cassius heard a heavy sigh. "_Why_ can't you just go away?" Severus said in a very annoyed tone. 

"Because I still haven't said what I wanted to say." Cassius responded.

"Well then, say it!" 

Cassius carefully pushed the door open, to walk into a room completely filled with cases containing potions, herbs, and books, probably all about potions. The room wasn't that big, but every available space was used. While Cassius walked past the largest bookcase, his mouth hanging open of fascination, he stroked the back of the books. Then he continued his little voyage of discovery, and strode forward to the cauldron that grabbed his attention. He watched the simmering of the green liquid, and recognised the vapours and colour. He surprised looked up to Severus. "This is a Sting-potion, isn't it? But that's dangerous!" 

"True," Severus grumbled. "So you'd better not come to close." 

Cassius quickly jumped away from a splatter. "What do you need it for?"

Severus hesitated a second, but then answered slowly; "Voldemort asked me to brew some."

Cassius startled at Severus' use of the name, but didn't say anything about it. Instead, he changed subject. "Oh, yes- what I came for. Albus asked if you had still thought about the socks."

Severus frowned at first, but then his expression became one of anger. "Yes, I have. And if he asks, I stored them in the room on the third floor, because it was the only room that could hold all of them."

Cassius stared at the ground. "I'm sorry," he mumbled. "I would've helped if I hadn't passed out."

Cassius saw Severus highly doubted that. "If that's what you came for, goodbye then."

"There's one more thing…" He looked up from the ground to see Severus' suspicious gaze. "Well, we—I and the 5th years—are currently working on a chapter about dark potions, and as I'm not so good at potions, I hoped you could tell them some more about it, and maybe bring something along?"

Severus looked at him in horror. "I don't think so." 

He started to walk out of the room, but Cassius ran after him. "Oh, come on, why not? It won't do you any harm! The students will be thrilled when I tell them you will be teaching them!" Cassius laughed. 

"Shut up, Ingaster." Severus spat, and started to walk faster. They were now in a dark corridor, and Cassius couldn't see a thing.

"Alright, I shouldn't have said that, but I really am terrible at potions. And besides, I thought you wanted the DADA job."

"Who told you that nonsense?" Severus' attempt to sound indifferent failed. 

"Don't deny it, everybody knows..- Ouch! Why are you stopping?" Cassius had bumped into Severus, who suddenly stood still. 

"Because I can't unlock the door while walking. _Alohomora._" 

A door opened, and some light—not much, as there hardly was any light in the dungeons—shone into Cassius' eyes. Severus walked back to his desk. Cassius followed him. 

"So? You'll do it?" Cassius asked with more than just a hint of hope. 

"Absolutely not." 

Cassius sat down on a chair. "Why not? Minerva volunteered to help me too." 

"I am NOT Minerva." 

"I never said THAT." Cassius sighed. The man was beginning to annoy him. "Severus, you are such a spoilsport. Always withdrawn, and the only contact you make is in the shape of sarcastic comments. You really need to-" 

"I do not need your advice. And stop talking like you're my muggle head doctor." He wrote on some parchment. 

"I'm not talking like a psychiatrist, so will you shut up and listen?" The bossy tone made Severus look up from his desk, and Cassius was glad he had finally got his attention. "Good. Er- now what was it that I wanted to say?" 

Severus rolled his eyes, and stood up from his desk. He walked past Cassius, who followed him again. He was not going to get rid of him that easy. "Where are you going?" 

"To my office. Where it is quiet." Severus added coldly. 

Cassius gave up. Without saying another word, he took the other way and went back to his room. 

*~*~*~*

Cassius sat in his room, gazing into the fire. Outside a storm was raging, and Cassius attentively listened to the raindrops that were hitting his window. It was 3 am, but he couldn't sleep. He imitated the thunder by tapping with his fingers on the couch. Like he was just awoken from a shock, Cassius rose on his feet, and grabbed a piece of parchment. After pondering a bit, he picked up a quill, and started to write, slowly. First the salutation, but after that, he stopped. What _could_ he say? Everything seemed so ridiculous. He sighed, and let his chin rest on his chest. "If I was the ground," he said to himself, "would I still feel so helpless?" 

As an answer, there was a loud thunderclap and lightning, and Cassius startled. He walked to the window, and by the next lightning he realised the thunder was hanging above the castle. He changed his pyjama for robes, and walked to the Great Hall. Of course it was completely empty, and Cassius' footsteps resounded. He walked to a table, and lay down on it, his face turned to the ceiling. It was wonderful how the lightning appeared at the same time as he heard the thunder. Cassius didn't know how long he lay there, but suddenly the storm subsided, and it was already becoming light. He stood up with pain in his back, and stumbled to his seat on the teachers' table. There he waited for the others to come in. The first ones were some 3rd years, and they looked so sleepy that Cassius didn't think they had noticed him. The first teacher was Professor Vector, but when she greeted him, he didn't respond. He was glad she didn't start a conversation with him. 

Though he had to talk, when Albus came in. His clothes hurt Cassius' eyes; he had a red robe with yellow balloons, and his face wasn't drowsy at all.

"Good morning, Cassius!" he said with loud voice, so everybody in the Great Hall started. 

"Morning, Headmaster," Cassius mumbled, "What's that festive dress for?"

"Well, have you forgotten?" said Albus while he took his seat. "Today is Severus' birthday!"

Cassius' stopped breathing for a moment, and he became aware of a very irritating noise in his head. "But--" 

He kept silent for a moment, while Albus penetratingly looked at him. "Are you sure?" Cassius asked. 

"Yes, I'm really sure. But don't feel sorry if you haven't bought him any presents; I don't think it'll bother him. Ah—there he is." 

The doors of the Hall opened again, and Severus appeared. Cassius swallowed, and tried not to look at him too strikingly as he sat down. 

"Happy birthday, Severus!" Dumbledore said as he grabbed the Potions Master's hand, and shook it powerfully. The students giggled, but when Severus glared at them, they continued staring at the table. 

More and more students and teachers had entered, and in 10 minutes everybody seemed to be there. Breakfast had begun. Cassius tiredly looked around for something tasty. He stretched his arm to get some bread, and knocked over his cup with juice. He groaned, and quickly cleaned the mess up with a spell. With a yawn he poured in some coffee. When he drank it, Cassius immediately spit it out. His colleagues surprised looked up. "What is this?!" Cassius exclaimed. 

Severus raised his eyebrow. "It's coffee."

"-Without any sugar or milk," Albus added after looking into Cassius' cup. Some professors chuckled, and Cassius reddened. 

"Oh." he responded. He added some sugar, and drank the coffee. "And this," he muttered under his breath, "is only the beginning of the day…"


End file.
